📈Compound Interest Calculator
Compound interest is how small, regular savings turn into large sums over time. Enter a starting amount, a rate, and optional monthly contributions to see your money grow.
Last updated: · Reviewed by The CalcWise Team
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How to use this calculator
- Enter your starting balance and the annual rate of return you expect.
- Choose how many years your money will grow.
- Add an optional monthly contribution, then Calculate to see your future value.
How it works
Compound interest means you earn returns not only on your original money but also on the returns it has already generated. Over long periods this snowball effect dwarfs the contributions themselves.
Time is the most powerful ingredient. Starting earlier, even with smaller amounts, usually beats starting later with larger amounts — which is why regular monthly contributions over decades build serious wealth.
Example: $5,000 invested at 7% with $200/month added for 20 years grows to roughly $124,000 — of which only about $53,000 is money you put in.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is calculated only on your original amount. Compound interest is calculated on the original amount plus all previously earned interest, so it grows much faster.
How often does interest compound here?
This calculator compounds monthly, which matches most savings and investment accounts and applies your monthly contributions along the way.